I replaced a Kohler shower mixing valve to repair a leak. When I turn on the water to go to the new valve, the water comes out of the shower head and the Kohler handle will not control the flow or shut off the water.

We need the model number of the valve.
When I turn on the water to go to the new valve, the water comes out of the shower head and the Kohler handle will not control the flow or shut off the water.
This is why I ALWAYS insist that the supplies and valve body be flushed out before reassembling a new valve. Turn off the water and open up the valve. Remove the cartridge and check and clean the inlet ports. Now turn the water on to flush uot the supplies and open valve body. Better now? Good luck and thank you for rating my reply. Tom

Looks like either cartridge was not put in correctly ( was not lined up with notch ) or handle is not engaging meaning it is not attached properly.

The first time I put in a new shower mixing valve I forgot to remove the cartridge before soldering and the heat obviously warped the seals. Embarrassing...